Rotary machine apex seal

ABSTRACT

A rotary machine apex seal arrangement having nested semicircular seal members of different diameter with the leading edge of the larger diameter seal member providing a leading seal and the trailing edge of the smaller diameter seal member providing a trailing seal with the machine&#39;&#39;s internal peripheral wall, both seal members being mounted for relative rotational movement to compensate for wear at the two sealing edges and also being mounted for rocking movement on the rotor to compensate for the contour of the wall.

United States Patent [1 1 ROTARY MACHINE APEX SEAL [75] Inventor: Nathaniel B. Kell, Indianapolis, Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Feb. 29, 1972 [21] Appl. No.: 230,316

[52] U.S. Cl 418/113, 418/117, 418/122 [51] Int. CL... F01c 19/02, F040 15/00, F04c 27/00 [58] Field of Search ..418/113, 117,122, 418/123; 277/81 P; 123/801 [56] References Cited UNITED STATES PATENTS 3,169,695 2/1965 Wankel 418/123 3,205,872 9/1965 Pomasanow 418/122 3,238,929 3/1966 Brodbeck et a1. 123/801 FOREIGN PATENTS OR APPLICATIONS 1,189,789 3/1965 Germany 418/118 June 19, 1973 1,247,094 8/1967 Germany 277/81 P Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrablik Attorney-J. L. Carpenter and R. Phillips [57] ABSTRACT A rotary machine apex seal arrangement having nested semicircular seal members of different diameter with the leading edge of the larger diameter seal member providing a leading'seal and the trailing edge of the smaller diameter seal member providing a trailing seal with the machines internal peripheral wall, both seal members being mounted for relative rotational movement to compensate for wear at the two sealing edges and also being mounted for rocking movement on the rotor to compensate for the contour of the wall.

4 Claims, 5 Drawing Figures Patented June 19, 1973 3,740,175

50 35 51 I v V V 824 ROTARY MACHINE APEX SEAL This invention relates to rotary machine apex seals and more particularly to rotary machine apex seals providing labyrinth sealing.

In rotary machines such as rotary combustion engines, pumps, compressors, and the like, wherein a seal arrangement is provided at each rotor apex to continuously sealingly engage an internal peripheral wall in the machine to separate the machines working chambers which rotate with the rotor, there are more demands on such sealing as compared with the sealing in reciprocating piston machines since in the former you want to avoid leakage between the working chambers whereas in the latter leakage is normally to the crankcase. Furthermore, in such rotary machines, the angle between the apex seal and the peripheral wall normally changes during rotor rotation because of the irregular curvature of this wall with the result that conventional type labyrinth sealing which will remain efficient as seal wear occurs during machine operation is not normally readily adaptable to such angle change.

The apex seal arrangement according to the present invention is disclosed in a rotary machine having a rotor housing with an internal peripheral wall wherein a rotor is rotatable relative to this wall and sealing is normally provided between each rotor apex and the wall to separate the machines working chambers which rotate with the rotor. Each of the apex seal arrangements according to the present invention comprise a pair of semicircular seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation. The seal member having the larger diameter has its large diameter surface continuously sealingly engaged with and rotatably supported by a semicircular surface in each rotor apex and the small diameter seal member has its large diameter surface continuously sealingly engaged with and rotatably supported by the small diameter surface of the large diameter seal member. A spring is mounted between the small diameter seal member and the peripheral wall and operatively engages both seal members to bias these members to rotate in opposite directions about a common axis to continuously engage the leading edge of the large diameter seal member and the trailing edge of the small diameter seal member with the peripheral wall as the rotor rotates. The seal assembly rocks in relation to the rotor to accommodate the contour of the peripheral wall and the spring forces counter-rotation of the seal members to compensate for seal wear at the leading and trailing edges.

An object of the present invention is to provide a new and improved rotary machine apex seal.

Another object is to provide in a rotary machine apex seal arrangement a pair of nested seal members which are biased for counter-rotation so that the leading edge ofone of the seal members and the trailing edge of the other seal member are continuously engaged with the inner peripheral wall and with both seal members mounted for rocking movement on the machines rotor to compensate for the contour of the peripheral wall as the rotor rotates.

Another object is to provide in a rotary machine a rotor apex seal arrangement wherein a spring biases a pair of nested semicircular seal members so that the leading edge of one of the seal members and the trailing edge of the other seal member are continuously biased into sealing engagement with the machines inner peripheral wall and wherein the two seal members are mounted for rocking movement on the rotor to compensate for the contour of the peripheral wall as the rotor rotates.

Another object is to provide an apex seal arrangement for a rotary machine wherein labyrinth type sealing is effected by a pair of nested seal members which are mounted for relative rotation about a seal axis at each rotor apex and also for movement about this axis relative to the rotor and are biased so that the leading edge of one of the seal members and the trailing edge of the other seal member continuously engage and follow the contour of the machines inner peripheral wall as the rotor rotates to compensate for both wear of the seal members at the sealing edges and also the contour of the peripheral wall.

These and other objects of the present invention will become more apparent from the following description and accompanying drawing in which:

FIG. 1 is a partial transverse sectional view of a rotary machine having apex seal arrangements according to the present invention.

FIG. 2 is a view of one of the apex seal arrangements taken along the line 22 in FIG. 1.

FIG. 3 is a view of the apex seall arrangement taken along the line 3-3 in FIG. 2.

FIG. 4 is a view of the apex seal arrangement taken along the line 4-4 in FIG. 2.

FIG. 5 is an exploded view of the apex seal arrangement of FIG. 1.

The apex seal arrangement according to the present invention is for use in rotary machines including rotary combustion engines, compressors, pumps, and the like. Referring to FIGS. 1 and 2, the rotary machine may, for example, be an internal combustion rotary engine of the Wankel type comprising a stationary outer body or housing 10 having a rotor cavity 12 that is defined by an inwardly facing peripheral wall 14 and a pair of axially spaced side walls 16. In the Wankel engine the peripheral wall 14 is in the shape of a two-lobed epitrochoid or a curve parallel thereto and a rotor 18 having the general shape of a triangle having three faces 20, of which only portions of two are shown, is mounted in the rotor cavity 12 on the eccentric of an output shaft, not shown, which is aligned with the cavitys axis. Gearing, not shown, between the housing 10 and the rotor 18 enforces a fixed, cyclic relation between the rotor and output shaft and the rotor face-s cooperate with the peripheral wall and with the end walls to define three variable volume combustion or working chambers 22 of which only portions of two are shown. Chambers 22 are spaced around the rotor and move with the rotor within the housing as the rotor rotates about its axis while planetating with respect to the output axis. Suitable fuel-air delivery and exhaust provisions, not shown, provide for periodic admission of fuel-air mixture and exhaust of the products of combustion from each chamber as the rotor rotates with each chamber undergoing intake, compression, expansion and exhaust to provide a power phase for each revolution of the engine output. The structure thus far described is conventional and operates efficiently assuming there is effective sealing between the working chambers of the engine.

An apex seal arrangement 24 according to the present invention is mounted on each of the rotors three apexes of which only one apex is shown for sealing the adjoining working chambers of the engine. Each apex seal arrangement 24 is generally of the labyrinth type and comprises a pair of semicircular seal members 26 and 28 with the seal member 26 being of larger diameter than the other seal member 28. The large diameter seal member 26 has its large diameter convex semicircular surface 29 slidably supported by and sealingly engaged with a concave semicircular surface 30 in an apex cap 31 as best shown in FIGS. 1, 3 and 4. Cap 31 is secured by screws 32 to the rotor 18 with its outer surface forming portions of the rotor faces. The large diameter seal member 26 as best shown in FIGS. 1, 3, 4 and further has a pair of axially spaced, circumferentially extending, dovetail ribs or tongues 33 which project from surface 29 and are engaged in matching dovetail grooves 34 in surface 30 of apex cap 31 to retain the seal member 26 on the cap while permitting movement of seal member 26 about its axis which is indicated at 35 in FIG. 1. The purpose of the detachable cap 31 is so that each of the seal arrangements 24 can be installed as a unit on the rotor to facilitate testing, machining, assembly, choice of compatible materials or replacement of wearable parts. When such type of assembly is not desired, it will be understood that the semicircular surface 30 may be formed directly on the rotor 18.

The small diameter seal member 28 is nested on the large diameter seal member 26 with its large diameter convex semicircular surface 36 slidably supported and sealingly engaged by the slightly larger diameter convex semicircular surface 37 of the other seal member 26. Thus, the two seal members 26 and 28 are capable of angular movement or rotation relative to each other about their common axis and in addition both seal members 26 and 28 are capable of rocking movement relative to the rotor 18 about this same axis. The two seal members 26 and 28 are retained together by a pair of axially spaced pins 38 which are fixed to the large diameter seal member 26 and extend through circumferentially extending, axially spaced slots 39 in the small diameter seal member 28 as best shown in FIG. 2, 3 and 4. The pins 38 each have a shoulder 40 which engages the seal member 28 to prevent separation of the seal members while the slots 39 permit limited relative rotation of the seal members.

Referring to FIGS. 1, 2, 3 and 5, an expansible spring 41 for biasing the seal members 26 and 28 has an ogee shape with its main body located in the space between the small diameter seal member 28 and the peripheral wall 14. The spring 41 has a short end 42 hooked under an angled wall portion 43 of an axially extending slot 44 through the mid portion of the small diameter seal member 28. The longer end 45 of the spring 41 extends through slot 44 and is anchored in an axially extending slot 46 in the surface 37 of the large diameter seal member 26.

The seal assembly is installed relative to the direction of rotor rotation indicated by the arrow in FIG. 1 so that a rounded edge 48 of the large diameter seal member 26 and a rounded edge 50 of the small diameter seal member 28 are both biased by the spring 41 to simultaneously engage the peripheral wall 14 with the seal edge 48 thus leading the seal edge 50. With this arrangement there is clearance between the leading edge 51 of the small diameter seal member 28 and peripheral wall 14 and also between the trailing edge 52 of the large diameter seal member 26 and this wall. Sealing between the rotor 18 and the housing side walls 16 is provided by pairs of parallel side sealing strips 54 which are mounted in accommodating side seal grooves in the sides of the rotor and extend between and sealingly abut with the surfaces 29 of the large diameter seal elements 26 at adjacent apexes.

In the operation of the apex seal arrangements, the spring 41 biases the seal elements 26 and 28 in opposite directions about their common axis 35 to continuously maintain sealing engagement of the leading seal edge 48 and the trailing seal edge 50 of these respective seal members with the peripheral wall 14 as the rotor 18 rotates and with relative angular movement between these members forced by this spring bias to compensate for wear occurring at these seal edges. With this rela-.

tionship of the leading and trailing seals relative to the noncontacting seal member edges, foreign material such as results from the combustion process is prevented from accumulating between the noncontacting leading edge 51 of the small diameter seal member 28 and the peripheral wall 14 and from between the noncontacting trailing edge 52 of the large diameter seal member 26 and the peripheral wall which accumulation, if permitted to occur, would tend to force the sealing edges 48 and 50 into the peripheral wall. In addition, as the rotor rotates within the rotor housing, both seal members 26 and 28 while they are maintained in sealing contact with the peripheral wall 14 are permitted to rock about axis 35 relative to the rotor 18 to compensate for the irregular curvature of the peripheral wall 14, the extremes of rocking angularity for the seal assembly each side of the center position being shown in FIG. 1 and indicated as the angle A. The dove-tail ribs 33 of the large. diameter seal member 26 are of sufficient extent so that they clear the rotor faces 20 by slightly less than the extreme rocking angle A as indicated by the smaller angle B so that during such rocking movement the ribs-act to clean the grooves 34 to prevent buildup of foreign matter therein.

The above described embodiment is illustrative of the invention which may be modified within the scope of the appended claims.

I claim:

1. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation, one of said seal members continuously sealingly engaged with and supported by said rotor for angular movement about an axis fixed with respect to said rotor, the other of said seal members continuously sealingly engaged with and supported by said one seal member for angular movement about said axis, bias means for biasing said seal members to move in opposite directions about said axis to effect continuous engagement of the leading edge of one of said seal members and the trailing edge of the other of said seal members with said peripheral wall.

2. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation, a semicircular surface on said rotor, one of said seal members having a first semicircular surface slidably supported by and continuously sealingly engaged with said semicircular surface on said rotor, said one seal member also having a second semicircular surface of smaller diameter than said first semicircular surface, the other of said seal members having a semicircular surface slidably supported by and continuously sealingly engaged with said second semicircular surface of said one seal member, spring means biasing said seal members to slide in opposite directions at said contacting surfaces to effect continuous engagement of the leading edge of one of said seal members and the trailing edged the other of said seal members with said peripheral wall.

3. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation, said rotor having a concave semicircular surface, one of said seal members having a convex semicircular surface continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface on said rotor, said one seal member also having a concave semicircular surface of smaller diameter than its convex semicircular surface, the other of said seal members having a convex semicircular surface having a diameter approximately equal to the diameter of said concave semicircular surface of said one seal member continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface of said one seal member, said other seal member having an opening therethrough opposite said one seal member, a spring mounted between said other seal member and said peripheral wall engaging said other seal member and extending through said opening to engage said one seal member and prestressed to bias said seal mem bers to slide in opposite directions at said contacting surfaces to continuously engage the leading edge of said one seal member and the trailing edge of said other seal member with said peripheral wall.

4. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation, said rotor having a concave semicircular surface, one of said seal members having a convex semicircular surface continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface on said rotor, said one seal member also having a concave semicircular surface of smaller diameter than its convex semicircular surface, said one seal member and said rotor having cooperating rib and groove means for retaining said one seal member on said rotor while per mitting the sliding movement of said one seal member, the other of said seal members having a convex semicircular surface having a diameter approximately equal to the diameter of said concave semicircular surface of said one seal member continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface of said one seal member, said seal members having cooperating pin and groove means for preventing separation of said seal members while permitting the sliding movement therebetween, said other seal member having an opening therethrough opposite said one seal member, a spring mounted between said other seal member and said peripheral wall engaging said other seal member and extending through said opening to engage said one seal member and prestressed to bias said seal members to slide in opposite directions at said contacting surfaces to continuously engage the leading edge of said one seal member and the trailing edge of said other seal member with said peripheral wall. 

1. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation, one of said seal members continuously sealingly engaged with and supported by said rotor for angular movement about an axis fixed with respect to said rotor, the other of said seal members continuously sealingly engaged with and supported by said one seal member for angular movement about said axis, bias means for biasing said seal members to move in opposite directions about said axis to effect continuous engagement of the leading edge of one of said seal members and the trailing edge of the other of said seal members with said peripheral wall.
 2. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation, a semicircular surface on said rotor, one of said seal members having a first semicircular surface slidably supported by and continuously sealingly engaged with said semicircular surface on said rotor, said one seal member also having a second semicircular surface of smaller diameter than said first semicircular surface, the other of said seal members having a semicircular surface slidably supported by and continuously sealingly engaged with said second semicircular surface of said one seal member, spring means biasing said seal members to slide in opposite directions at said contacting surfaces to effect continuous engagement of the leading edge of one of said seal members and the trailing edge of the other of said seal members with said peripheral wall.
 3. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative tO the direction of rotor rotation, said rotor having a concave semicircular surface, one of said seal members having a convex semicircular surface continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface on said rotor, said one seal member also having a concave semicircular surface of smaller diameter than its convex semicircular surface, the other of said seal members having a convex semicircular surface having a diameter approximately equal to the diameter of said concave semicircular surface of said one seal member continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface of said one seal member, said other seal member having an opening therethrough opposite said one seal member, a spring mounted between said other seal member and said peripheral wall engaging said other seal member and extending through said opening to engage said one seal member and prestressed to bias said seal members to slide in opposite directions at said contacting surfaces to continuously engage the leading edge of said one seal member and the trailing edge of said other seal member with said peripheral wall.
 4. In a rotary machine, a rotor housing having an internal peripheral wall, a rotor rotatable relative to said peripheral wall, and seal means for continuously providing sealing between said peripheral wall and said rotor as said rotor rotates comprising a pair of seal members each having a leading edge and a trailing edge relative to the direction of rotor rotation, said rotor having a concave semicircular surface, one of said seal members having a convex semicircular surface continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface on said rotor, said one seal member also having a concave semicircular surface of smaller diameter than its convex semicircular surface, said one seal member and said rotor having cooperating rib and groove means for retaining said one seal member on said rotor while permitting the sliding movement of said one seal member, the other of said seal members having a convex semicircular surface having a diameter approximately equal to the diameter of said concave semicircular surface of said one seal member continuously sealingly engaged with and supported for sliding movement by said concave semicircular surface of said one seal member, said seal members having cooperating pin and groove means for preventing separation of said seal members while permitting the sliding movement therebetween, said other seal member having an opening therethrough opposite said one seal member, a spring mounted between said other seal member and said peripheral wall engaging said other seal member and extending through said opening to engage said one seal member and prestressed to bias said seal members to slide in opposite directions at said contacting surfaces to continuously engage the leading edge of said one seal member and the trailing edge of said other seal member with said peripheral wall. 